Unit 5- Topic 20

Functional group= C=C Test: add bromine water (Br2 (aq)) Observation: bromine decolourises immediately

Bromine water is decolourised very slowly

Test: warm with NaOH (aq) and then add dilute HNO3, followed by a few drop of AgNO3(aq) Observations: R-Cl= produces white ppt. Ppt is insoluble in dilute NH3 R-Br= produces cream ppt. Ppt is insoluble in dilute NH3 but soluble in concentrated NH3 R-I= produces yellow ppt. Ppt is insoluble both dilute NH3 and concentrated

Functional group= -OH Test= add solid PCl5 Observation= misty fumes Both alcohols and Carboxylic acids produce misty fumes, but not phenols

Functional group= (RCH2OH) Test= add acidified K2Cr2O7 solution and warm Observation= solution turns from orange to green The organic product of this reaction produces a silver mirror with Tollen’s reagent

Functional group= (R2CHOH) Test=add acidified K2Cr2O7 solution and warm Observation= solution turns from orange to green Notes= the organic product does not produce a silver mirror with Tollen’s reagent

Functional group: (C=O) Test: add 2,4-DNPH Observation: orange precipitate Notes:both aldehydes and ketones produce and orange ppt

Functional group=(RCHO) Test= add Tollen’s reagent and warm Observation= silver mirror forms Notes= Fehling’s solution can also be used. Ketones do not react with Tollen’s or Fehling

Test= add alkaline solution of iodine and warm Observation= yellow ppt forms Notes= known as triiodomethane or iodoform test

Functional group= R-COOH Test= add NaHCO3 or Na2CO3 and warm if necessary Observation= bubbles of gas

Functional group= benzene- OH Test= addd bromine water Observations= bromine immeaditely decolourises and a white precipitate forms Notes= phenylamine produces same results. Phenol is soluble in NaOH but insoluble in dilute HCl. Phenylamine is insoluble in NaOH but soluble in dilute HCl

1- Reacting a halogenoalkane with a cyanide ion forms a nitrile with one more carbon atom that the halogenoalkane 2- the addition of hydrogen cyanide to a carbonyl compound 3- the alkylation of benzene, which introduces an alkyl group into a benzene ring 4-the use of Grignard reagents

They are organometallic compounds containing magnesium. They are made by heating under reflux the chosen halogenoalkane with magnesium in a solvent of dry ether. Bromoalkanes are the preferred halogenoalkane. Grignard reagents contain magnesium covalently bonded to both the alkyl group and the halogen. General equation: R - Br + Mg —> R - Mg - Br Grignard reagents react with water so they are made nd used in a solvent of dry ether

RMgBr + CO2 -> RCOOH, grignard + carbon dioxide -> carboxylic acid RMgBr + CH2O -> RCH2OH, grignard + methanal -> primary alcohol RMgBr + R’CHO -> RR’CHOH, grignard + aldehyde -> secondary alcohol RMgBr + R’COR’’ -> RR’R’’COH, grignard + ketone -> tertiary alcohol After the reaction is complete, dilute acid is added to obtain the desired organic product

-can affect if the compounds is going to act as nucleophilic or electrophile -if they are susceptible to addition reactions or substitution -if they are easily oxidised or easily reduced

-check is carbon chain length has increased or decreased -by looking at final product and working back to the starting compound -by looking at the starting compound and thinking of types of reactions it can undergo

Equation: CH2=CH2 + HX -> CH3CH2X Reagent: hydrogen halide Conditions: mix the gases at room temperature

Equation: RX + NaOH —> ROH + NaX Reagent: aqueous sodium hydroxide Conditions: heat under reflux

Equation: RX + KCN —> RCN + KX Reagent: alcoholic potassium cyanide Conditions: heat under reflux

Equation: RX + 2NH3 —> RNH2 + NH4X Reagent: aqueous ammonia Conditions: heat under reflux

Equation: ROH + PCl5 —> RCl + HCl + POCl3 Reagent: phosphorus (V) chloride Conditions: room temperature

Equation: ROH + HBr —> RBr + H2O Reagent: 50% concentrated sulfuric acid and potassium bromide Conditions: warm

Equation: 3ROH + PI3 —> 3RI + H3PO3 Reagent: red phosphorus and iodine Conditions: heat under reflux

Equation: RCH2OH + [O] —> RCHO + H2O Reagent: potassium dichromate (Vl) and dilute sulfuric acid Conditions: add the reagent to hot alcohol and allow the aldehyde to distil off as it is formed